Operating Principle Of Two-Speed Motor - Kubota u15-3 Workshop Manual

3) Operating principle of two-speed motor

The swash plate has two faces I and II on the surface opposite to the shoe-sliding surface and sup-
ported by the two balls fixed in the body 2 .
The ball is positioned eccentrically above the central axis. In the 1st speed state, therefore, the face
II is pressed against the body 2 by hydraulic oil force applied to the piston and the spring force in the
cylinder barrel and the swash plate angle becomes . At this time, the motor is of large capacity.
When the speed selector lever is switched to the g2nd speed position, the operating pressure is con-
ducted through the two-speed spool to the control room and the control piston moves until the face II
of the swash plate touches the body 2, fixing the swash plate angle at . At this time, the motor is of
small capacity.
When the engine is stopped, the control room is connected to the drain port through the two-speed
spool and the swash plate is returned to the 1st speed position by the spring force. At the time of
starting, therefore, the motor is always in the 1st speed state.
(1) Swash plate
(2) Shoe
(3) Piston
(4) Spring
(5) Cylinder barrel
(6) Ball
(7) Body 2
(8) Face II
(9) Face I
(10) Control room
(11) Control piston
(12) Operating pressure
II-81
WSM U15-3